1. Field of the Invention
The present invention is directed to an instrument capable of measuring angles between walls, floors, and ceilings within a room and measuring the spring angle and calculating and displaying the appropriate angles for cutting miter joints for the installation of trim and crown molding.
2. Description of Related Art
Throughout the history of architecture, molding has been used as a decorative embellishment and a means to cover imperfections in construction. In the present day, it is used in some form in most buildings ranging from massive edifices to modest homesteads. Typically, modern molding consist of strips of rigid or semi-rigid material including wood, plastic, rubber and the like, often having a decorative feature, and is used to cover intersections between building elements such as walls, floors, and ceilings as well as around doors and windows.
Where a turn is required, molding can be installed with joints where one piece simply abuts the adjacent piece, i.e. butt joints. However, when the molding has a decorative pattern, frequently employed are mitered joints where each of the adjacent pieces of each joint is cut on an angle. Generally, a mitered joint is considered to have a more finished and pleasing appearance than a simple butt joint but it requires greater precision. Usually, the miter angle is half of the angle of the required turn. For example, if molding must make a right angle, i.e., 90°, turn, each of the adjacent pieces is cut to a 45° angle where they are to be joined.
Making the appropriate cuts is a relatively straightforward operation if the piece to be cut is cut at the same angular orientation at which it is intended to be installed. The major problem with cutting trim arises from the fact that trim is usually cut lying flat on its back rather than at the installation orientation where it meets the wall, floor or ceiling. This change in orientation means that a 45° cut can no longer be achieved by simply setting a miter saw for a 45° miter or 45° bevel angle. A complex, unintuitive combination of miter and bevel angles is needed to achieve what otherwise would be a simple task. This calculation is a challenge to even an experienced craftsman who will often resort to trial and error. Specialized protractors and related angle measuring and calculating devises to facilitate making miters joints have appeared in the art. For example, see U.S. Pat. Nos. 5,040,298 and 6,829,837 as well as digital protractor DWM40L marketed by Bosch which assumes particular crown angles without a way to calculate the actual crown angle at which the trim will be installed.